Webflux - Spring Boot - oAuth2 client with http proxy support

I'm struggeling to correctly setup the webflux-weblient with oauth2 behind a proxy.

It seems, that the ServerOAuth2AuthorizedClientExchangeFilterFunction uses a new instance of a webclient , which doesn't contain my proxy-configuration.

OAuth2-Config

    ServerOAuth2AuthorizedClientExchangeFilterFunction oauth2ClientFilter = new ServerOAuth2AuthorizedClientExchangeFilterFunction(
      clientRegistrations,
      new UnAuthenticatedServerOAuth2AuthorizedClientRepository());
   oauth2ClientFilter.setDefaultClientRegistrationId("azure");

OAuth2AuthorizedClientResolver.class contains:

private ReactiveOAuth2AccessTokenResponseClient<OAuth2ClientCredentialsGrantRequest> clientCredentialsTokenResponseClient = new WebClientReactiveClientCredentialsTokenResponseClient();

The WebClientReactiveClientCredentialsTokenResponseClient.java creates a new webclient as follows:

private WebClient webClient = WebClient.builder().build();

Does anybody have a sample how to correctly setup a http-proxy for the oauth2 client?

Thanks to the incomplete answer of @abhinaba-chakraborty, I managed to set proxy based on the JVM params inside the WebClient for WebClientReactiveClientCredentialsTokenResponseClient.

Here is my pieces of code to help other people with the same issue :

This is a helper function to take the JVM params and set them to the HttpClient

    public HttpClient proxyHttpClient() {
        String proxyHost = System.getProperty("https.proxyHost");
        String proxyPort = System.getProperty("https.proxyPort");

        if (proxyHost == null && proxyPort == null) {
            return HttpClient.create();
        }

        return HttpClient.create()
                .tcpConfiguration(tcpClient ->
                        tcpClient.proxy(proxy ->
                                proxy.type(ProxyProvider.Proxy.HTTP).host(proxyHost).port(Integer.valueOf(proxyPort))
                        )
                );
    }

This is how to configure the OAuth2Client for the WebClient used for calling outside systems (based on the response of @abhinaba-chakraborty). Note the function named configureHttpProxy:

    @Bean
    public ReactiveOAuth2AuthorizedClientManager authorizedClientManager(
            ReactiveClientRegistrationRepository clientRegistrationRepository,
            ReactiveOAuth2AuthorizedClientService authorizedClientService) {

        return configureHttpProxy(
                new AuthorizedClientServiceReactiveOAuth2AuthorizedClientManager(
                        clientRegistrationRepository,
                        authorizedClientService
                )
        );
    }

    @Bean
    WebClient webClient(ReactiveOAuth2AuthorizedClientManager authorizedClientManager) {
        ServerOAuth2AuthorizedClientExchangeFilterFunction oauth2Client = new ServerOAuth2AuthorizedClientExchangeFilterFunction(authorizedClientManager);
        oauth2Client.setDefaultClientRegistrationId("registration_id");
        return WebClient.builder()
                .filter(oauth2Client)
                .clientConnector(new ReactorClientHttpConnector(HttpClient.create().wiretap(true)))
                .baseUrl(rdoWebClientProperties.getBaseUrl())
                .defaultHeader(rdoWebClientProperties.getApikeyName(), rdoWebClientProperties.getApikeyValue())
                .build();
    }

And here is the configureHttpProxy function:

    private AuthorizedClientServiceReactiveOAuth2AuthorizedClientManager configureHttpProxy(AuthorizedClientServiceReactiveOAuth2AuthorizedClientManager authorizedClientManager) {
        // set the webclient with proxy configuration in the ReactiveOAuth2AccessTokenResponseClient
        WebClientReactiveClientCredentialsTokenResponseClient tokenResponseClient = new WebClientReactiveClientCredentialsTokenResponseClient();
        tokenResponseClient.setWebClient(
                WebClient.builder()
                        .clientConnector(new ReactorClientHttpConnector(proxyHttpClient()))
                        .build()
        );

        // set the ReactiveOAuth2AccessTokenResponseClient with webclient configuration in the ReactiveOAuth2AuthorizedClientProvider
        ClientCredentialsReactiveOAuth2AuthorizedClientProvider authorizedClientProvider = new ClientCredentialsReactiveOAuth2AuthorizedClientProvider();
        authorizedClientProvider.setAccessTokenResponseClient(tokenResponseClient);

        // set the ReactiveOAuth2AuthorizedClientProvider in the ReactiveOAuth2AuthorizedClientManager
        authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);

        return authorizedClientManager;
    }

Hoping this will help.